Effect of Starvation on Amylase and Trypsin Activities at Two Developmental Stages of Artemia (San Francisco)
An apparent repressive control of amylase and trypsin respectively by starch and proteins of the diet were precedently demonstrated on artificial axenic media . Such a mechanism has been improved also on Artemia fed Platymonas sueccica in more usual rearing conditions. Artemia face a starvation period of 4–5 days during growth or at adult stage by increasing enzymatic activities when food was lacking. This compensatory mechanism was immediate for amylase but was delayed for trypsin depending on the duration of starvation and the decrease of internal protein content. This response time difference is hypothesized to be related to differences in circulating carbohydrates, proteins or amino acid pools in the hemolymph.
These results corroborate observations using artificial axenic media. They suggest that digestive enzyme synthesis is mediated through circulating carbohydrates, proteins or amino acids by a neuroendocrine system. They improve the compensatory model presently proposed and its use as a tool in nutritional requirement studies.